It is known to associate a locking device with a telescopic tube for fixing the telescopic tube in an extracted position.
Reducing production costs is a sensitive issue, in particular when the telescopic tube is used for applications that imply a high risk of contamination, for example due to long stays under the action of atmospheric agents, with a focus on use simplicity and on maintenance simplicity, as may be in a use in the building field.
Moreover, it is important to protect the adjusting device and prevent, where possible, the presence of projecting radial struts which may be an element of accident or damage to the clothing of the yard personnel or a pedestrian passing by.
Document DE-A-19527738 describes a bar on which a toothed bushing is movable and lockable. The manual adjustment of the bushing position along the rod and the related locking, however, may be improved.